In Long Term Evolution (LTE) networks, mobile applications and their corresponding higher data rate requirements are the latest phenomenon causing a tremendous need in power saving for mobile devices. Discontinuous Reception (DRX) is a method by which a User Equipment (UE) can switch off its receiver for a period of time, thus saving energy, while remaining in the Radio Resource Control (RRC) Connected state (or mode). DRX in Connected mode is a power saving mechanism in LTE networks. Since DRX saves battery power of the UE, usually at the expense of potential increase in latency, an optimization is needed to find the best tradeoff between latency and power savings.
Device-to-Device (D2D) Proximity Service (ProSe) capable UEs are UEs that can communicate with one another. Radio resource allocation and management is needed for D2D discovery for in-coverage scenarios. During the discovery time duration, which occurs periodically in the order of seconds, the D2D ProSe UEs may be either transmitting or receiving the discovery signals. Therefore, UEs are active and thus consuming power during discovery opportunity duration irrespective of the LTE states (i.e., idle or connected mode DRX States).